Thank you for this new information. Since Hanoi and Ho Chi Minh City disagree for time stamps as late as 1975, we need to add a Zone for Hanoi. The real jewel here is the indirect reference to the authoritative source"Lịch Việt Nam: thế kỉ XX–XXI (1901–2100) & Niên Biểu Lịch Sử Việt Nam" (2014) <http://bookaholic.vn/lich-viet-nam-the-ki-xx-xxi-1901-2100-va-bien-bieu-lich...>. I'd like to verify the information from this source if possible. For example, if I'm reading the website correctly the 1906 transition was on July 1, not June 9, but I'd like to check that against the book. I have requested a copy of the book from my library; it has a 2005 edition, which should suffice for our needs. This underscores the unreliability of our old source Shanks. We already knew Shanks was wrong for large swaths of the world in the 20th century. Even so, it's surprisingly bad for a U.S. source like Shanks to get South Vietnam wrong in 1973. Wasn't Shanks reading the newspapers?